Snowden reportedly made remarks as he met on Thursday with a German MP in Moscow. According to Russia Today, he passed a letter addressed to the German government and federal public prosecutor where he allegedly said he is ready to testify over Washington's probable wiretapping of Merkel’s phone.

During the meeting, Snowden made it “clear that he knows a lot,” Greens lawmaker Hans-Christian Stroebele was quoted as having told the ARD channel.

“He expressed his principle readiness to help clarify the situation. Basis for this is what we must create. That’s what we discussed for a long time and from all angles,” the MP said.

Snowden “is essentially prepared to come to Germany and give testimony, but the conditions must be discussed," clarified Stroebele, who is a member of the German parliament's control committee which is responsible for monitoring the work of intelligence agencies.

Snowden was told that he could potentially give evidence from Moscow. More details about the meeting are expected on Friday, according to Russia Today.

German Chancellor Angela Merkel dispatched the country’s top foreign affairs and intelligence advisers to Washington this week to further investigate the allegations that her cell phone was tapped by the NSA, the report which caused fierce outrage in Germany.

Following the first report on the spying on Merkel, the German Der Spiegel magazine further reported that Merkel's phone had appeared on a list of spying targets for over a decade, and was still under surveillance weeks before Obama visited Berlin in June.

A third report in the German newspaper Bild am Sonntag newspaper quoted U.S. intelligence sources as saying that Alexander had briefed Obama on the operation against Merkel in 2010.

The United States denied, however, that the President was personally informed for years of electronic surveillance against the German chancellor.

The German Federal Prosecutor’s Office may summon Snowden to be a witness in the case, German justice minister Sabine Leutheusser-Schnarrenberger has indicated.

“If our suspicions prove correct and a case is opened, the German Federal Prosecutor’s Office will have to consider the possibility of interrogating Snowden as a witness,” she said.

On August 1, Snowden was granted temporary asylum in Russia. He is free to stay in Russia until at least July 31, 2014, and his asylum status may be extended annually upon request.

Snowden leaked classified information to the Guardian and Washington Post pertaining to alleged NSA eavesdropping on telephone calls and emails of private citizens, then fled from his home in Hawaii, to a Moscow airport, via Hong Kong. After staying in the airport for more than a month, the Russian government decided to grant him political asylum.